PHENOLIC COMPOUNDS IN LAUREL WOOD: A NEW SOURCE OF PROANTHOCYANIDINS

Abstract

Laurel tree (Laurus nobilis L.) wood is a byproduct of the pruning of this tree widely cultivated for its aromatic leaves. The phenolic composition of laurel wood has not been reported yet. The aim of this work was to study the phenolic profile of an ethyl acetate extract of laurel wood in order to know its potential as a source of antioxidants and valuable compounds. Three flavan-3-ols, 4 dimeric B-type proanthocyanidins, and 2 trimeric A-type procyanidins were isolated by preparative column chromatography and semi-preparative HPLC, using a fast online post-column radical scavenging detection technique as guidance. All isolated compounds were fully characterized by spectroscopic (NMR, IR, UV) and spectrometric (MS) techniques. In addition, 17 minor proanthocyanidins were tentatively identified by liquid chromatography coupled to mass spectrometry (HPLC–ESI–MS). The extract was dominated by the presence of cinnamtannin B-1, a bioactive trimeric A-type procyanidin reported as a strong antioxidant of commercial value. According to the chemical composition found, it can be concluded that laurel wood is a renewable source of potential bioactive phenolic compounds.

Keywords:

• Laurus nobilis L. (Lauraceae)
• laurel wood
• agricultural wastes
• online HPLC radical scavenging
• HPLC–ESI–MS
• proanthocyanidins

ACKNOWLEDGEMENTS

Authors thank Fernando Altarejos-Gil, the laurel tree’s owner, for providing the laurel wood sample.

FUNDING

Authors wish to thank the University of Jaén for financial support through the project UJA081605. A.A.-A and A.T.-A were the recipients of a predoctoral fellowship granted by the University of Jaén and an employment contract linked to project UJA081605, respectively. Part of the work was supported by the Centro de Instrumentación Científico-Técnica of the University of Jaén.